The WMO notes that cracks in the Pine Island Glacier "have been growing rapidly" in the past several days according to satellite imagery.
The recent spate of warmth owes to a ridge of high pressure that has lingered over the region for several days. High-pressure systems feature sinking air, which favors milder temperatures.
This effect was amplified on a local level due to a "foehn" wind, characterised by air sweeping down a mountain that begins compressing as air pressures rise near the Earth's surface. That causes additional warming.
Moreover, a look at simulated atmospheric profiles around the time it hit the record indicated warmer air aloft than at the surface - meaning any air that mixed down to ground level could have had an additional leg up in warming.
It's been a monumental year for climate extremes, and we're only on day 38 of 2020. January was the warmest on record globally according to atmospheric monitoring group Copernicus, with records shattered in Europe and Asia.
"[This record] doesn't come as any surprise," wrote Eric Steig, a glaciologist studying climate change at the University of Washington. "Although there is decade-to-decade variability, the underlying trend across most of the continent is warming."
He says this record will likely broken again in the not-so-distant future.
"That warming has been particularly fast on the Antarctic Peninsula - where Esperanza is - in summer (the season [they're] now in). So we can expect these sorts of records to be set again and again, even if they aren't set every single year."
Additional extreme warmth is likely in the Antarctic Peninsula in the coming days.